Entering the 21st century, cultural trends are increasingly tending toward a happier life around the world, and awareness of the environment and sanitation has become widespread. Due to the spread of viral infections such as H1N1 flu, SARS, bird flu, and HIV, contamination by agricultural pesticides and heavy metals, and infectious diseases on a large scale such as foot-and-mouth disease and mad cow disease, the attention to the safety of food has increased and legal regulations have been tightened. Thus, anti-bacterial and virus disinfecting products are important for the sanitation and health of people and the economy.
Meanwhile, synthetic antiseptics currently used for food and cosmetics, and cleaning products for preventing the H1N1 flu are limited in their amount and uses due to their toxicity, and thus are not able to exhibit sufficient activity. In addition, due to chronic side effects, they actually pose a health threat. On the other hand, natural antiseptics are widely used due to the bad reputation of synthetic antiseptics and the preference for natural products derived from nature. However, natural antiseptics rarely exist in nature, and thus are difficult to find. They are composed of organic components, so that they decompose easily according to changes in the surrounding conditions including temperature, chemical substances, UV, and biological resistance.
However, anti-bacterial and virus disinfecting products derived from inorganic natural substances can overcome such disadvantages of the organic natural antiseptics.
Red clay is a mineral obtained from nature, which is widely spread in arid and semi-arid regions and covers about 10% of the Earth s surface. Red clay has a porous structure, and has characteristics of strong adsorption, deodorization, buffering, ion-exchange, and emission of far-infrared radiation, so that it is widely applied in construction materials, cosmetic additives, and other health-care products.
The main component of red clay, i.e., pure SiO2 or a natural mineral containing abundant SiO2, is changed into a water-soluble silicate by reaction with an alkali substance at a high temperature of 1400° C. or more when it is to be used as a corrosion and scale inhibitor or an agricultural fertilizer. However, in a conventional process, such a reaction is performed for a long time at a high temperature ranging from 1400 to 1700° C., which results in high production costs.